This invention relates a load detector device for an elevator, which detects the load on the elevator cages; this invention also relates to tension indicator devices for indicating the tensions of the main ropes by which the elevator cage is suspended in the hoist way.
FIGS. 1 and 2 show a load detector device for an elevator, disclosed, for example, in Japanese laid-open utility model No. 59-116361 or Japanese patent publicaion No. 39-16526. An elevator cage 1 is provided with an inverted U-shaped cross-sectional upper beam 1a, whose upper flat constitutes an anchoring plate 2 for the main ropes 4. The main ropes 4 are connected to the respective anchoring members, or shackle rods, 3, which extend through the anchoring plate 2. As shown in FIG. 2, elastic means 5, which comprises, for each anchoring member 3, a compression helical spring 5a fitted around the bottom end portion of an anchoring member 3 to bear upon the upper and lower spring seats 5b at both ends thereof, mounts the anchoring members 3 elastically to the anchoring plate 2, the elastic means 5 being disposed between the anchoring plate 2 and the nuts 6 screwed onto the threaded bottom end portion of the anchoring member 3.
Reference numeral 7 designates an activator member pivoted at an intermediate point thereof to the bottom surface of the upper beam 1a; the end portion of the activator member 7 situated to the side of the anchorinng members 3 is forked into support portions 7a, each opposing the bottom end of one of the anchoring member 3. Further, there is provided an urging member 7b consisting of a spring urging the activator member 7 so that the support portions 7a urge upward the bottom ends of the anchoring members 3. Reference numeral 8 designates a load detector consisting of a switch disposed on the bottom surface of the upper beam 1a to be activated by the rotation of the arms of the activator member 7.
One of the typical conventional rope anchoring devices for an elevator is constituted as described above. Thus, the cage 1 is suspended from the main ropes 4 via the anchroing members 3, the elastic means 5, and the upper beam 1a. When the load of the cage 1 increase, the elastic means 5 is compressed, and the anchoring members 3 move relatively upward with respect to the anchoring plate 2. As a result, the activator member 7 rotates, and, when the load of the cage exceeds a predetermined value, the laod detector 8 is activated. The activation of the load detector 8 triggers the necessary control of the elevator, such as that of the nonstop passing of floors due to the full capacity of the cage.
The load detector device of FIG. 2, however, has this problem: When the main ropes 4 are elongated with the passage of time, such temporal elongations of ropes are absorbed by the screwing-in of the nuts 6. In such case, the bottom ends of the anchoring members 3 are displaced with respect to the upper beam 1a to which the load detector 8 is mounted. Thus, each time the ropes 4 exhibit temporal elongations, the detector position of the load detector 8 should be adjusted anew.
By the way, the elevator devices for carrying freight and passengers are generally of the rope-type as the one described above. The rope-type elevator devices are further classified on the basis of the roping modes, such as 1:1 roping mode--as in the case described above--and 2:1 roping mode.
FIG. 3 shows another conventional 1:1 roping mode rope-type elevator device, which is similar to the one described above. An elevator cage 1 is supported within a cage frame which comprises: a pair of horizontal bottom frames 1i; a pair of vertial frames 1b fixed to the ends of the bottom frames 1i; and an upper beam 1a having a hat-shaped cross sectional form and spanning across the top ends of the pair of vertical frames 1b. Further, through the upper horizontal flat 2 of the upper beam 1a are formed a plurality of through-holes, through which shackle rods (anchoring members) 3 extend vertically to be vertically translatable therethrough. To the top ends of the shackle rods 3 are connected the main ropes 4 at one of the ends thereof, which ropes are wound around the sheave of the winding machine (not shown) in the machine room usually at the top of the hoist way of the elevator.
Incidentally, the projection lengths of the shackle rods 3 projecting from the upper surface 2 of the upper beam 1a can be adjusted by means of the nuts which are hidden within the upper beam 1a in FIG. 3.
On top of the front or entrance side of the cage 1 is attached a support member 1d having an inverted L-shaped cross sectional form. Spanned horizontally across the respective ends of the vertical side of the support member 1d and the pair of vertical frames 1b are connector members 1c. Further, stays 1h are spanned slantwise across the respective ends of the horizontal top flat of the suport member 1d and the respective ends of a side of the upper beam 1a. Furthermore, on the horizontal upper flat of the support member 1d is disposed a driving device 1j adjacent to a stay 1h; in addition, to the bottom edge of the vertical side of the support member 1d is fixed a rail 1k positioned directly above the entrance. Further, at the front bottom of the cage 1 is disposed a threshold 1f provided with a groove 1g positioned directly below the entrance. A rectangular door 1l is translatably fitted into the groove 1g and the rail 1k; the door 1l thus slides horizontally, being driven by the driving device 1j, so as to open and close the entrance. Thus, by means of the rotation of the sheave driven by the winding machine at the top of the hoist way, the plurality of the main ropes 4 are translated to move up and down the cage 1.
Next, the overall roping organization of the conventional 2:1 roping mode rope-type elevator device is described by reference to FIG. 4. Within a machine room 1n disposed at the top of the hoist way are disposed: a winding machine (not shown) provided with a sheave 1q; and a rotatable deflector wheel 1r positioned at the bottom side portion of the winding machine. Around the deflector wheel 1r and the sheave 1q are wound the main ropes 4, the respective ends of which extend through the holes through the floor 1p of the machine room 1n, to be suspended therefrom within the hoist way, respectively. Thus, one side of the main ropes 4 is wound around the pulley 1m of the cage 1 to be suspended from a side of the floor 1p via a buffer spring, etc.; the other side of the main ropes 4 is wound around the pulley 1t of the counterweight 1s to be suspended from the other side of the floor 1p via a buffer spring, etc.
Thus, when the sheave 1q rotates, the main ropes 4 are forwarded over the sheave 1q and the deflector wheel 1r, to effect a vertical translation of the cage 1 at 1/2 the speed of the main ropes 4.
By the way, generally speaking, the main ropes 4 are wound in parallel around the rope grooves of the sheave 1q, etc. If the elongations of the respective main ropes 4, and hence the tensions thereof, are not uniform, there arise inequalities among the respective loads born by the main ropes 4. This may result in frequent occurances of slips thereof with respect to the rope grooves of the sheave 1q, etc., which may generate failures occasioned by oscillations of the cage 1 or the abnormal abrasions of the main ropes 4.
Thus, it is necessary to adjust the tensions of the main ropes 4 to a uniform level. According to the conventional tension adjustment operations, as shown in Japanese published utility model No. 62-18610, the main ropes 4, each of which is given a predetermined tension, are cut to the same length, thereby securing the uniformity of the tensions of the main ropes 4.
However, in the initial state when the operation of the elevator device is started, the main ropes 4 are still new and thus are prone to be easily elongated under stress; in addition, they are under constant bending strains. As a result, the generation of a non-uniformity of the tensions of the main ropes 4 can hardly be avoided. Thus, in such a case, a spring-type balance is successively engaged by an operator, as shown in FIG. 3, with each one of the main ropes 4 and is pulled at right angles thereto (i.e., horizontally) so as to measure the tension thereof; on the basis of the measurements, the nuts are screwed or unscrewed, so as to adjust the projection lengths of the shackle rods 3. This adjustment operations, however, becomes very complicated when the number of the main ropes 4 is large; hence there arises the problem that the maintenance/inspection operations may suffer great delays.
Further, since the conventional tension adjustment operations have often been dependent on the operator's guess, non-uniformity of the tensions of the main ropes 4 has frequently been generated. Furthermore, in the case of the 2:1 roping mode rope-type elevator devices, there are a plurality of pulleys 1m and 1t between the two ends of the main ropes 4. Thus, a single adjustment operation is not sufficient for the complete tension adjustments of the whole length of the main ropes 4. Consequently, the tension adjustment operations should be repeated a number of times. Thus, the tension adjustment operations require a great deal of time and labor.